Roskilde Cathedral (Danish: Roskilde Domkirke), in the city of Roskilde on the Island of Zealand (Sjælland) in eastern Denmark, is a cathedral of the Lutheran Church of Denmark. It was the first Gothic cathedral to be built of brick and its construction encouraged the spread of this Brick Gothic style throughout Northern Europe. It was built during the 12th and 13th centuries, and incorporates both Gothic and Romanesque architectural features in its design. It was the only cathedral in Zealand until the 20th century, and its twin spires dominate the skyline of the town. Roskilde Cathedral has been the main burial site for Danish monarchs since the 15th century. As such, it has been significantly extended and altered over the centuries as individual rulers have added many burial chapels. Following the Danish Reformation in 1536, the Bishop's residence was moved to Copenhagen, and he from then on held the title Bishop of Zealand. Royal coronations normally took place in Copenhagen's Church of Our Lady or in the chapel of Frederiksborg Palace. The cathedral is a major tourist attraction, bringing in over 125,000 visitors annually. Since 1995 it has been listed as a UNESCO World Heritage Site. Since 1987, the cathedral has been the home of one of Denmark's leading boys' choirs, the Roskilde Cathedral Boys' Choir. The choir, soon celebrating its 20th birthday, is a key resource in the parish youth work. All choristers go to normal school but meet up 2-3 times a week to rehearse. Every second year the choir travels abroad; destinations being as different as New Zealand, Scandinavia, England, Greenland, France and Canada. A working church, it also hosts concerts throughout the year.